Test Chamber Cooling Coil Control to Limit Humidity Loss
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Solution Overview
Problem
Current temperature and humidity control systems in test chambers face challenges in maintaining high temperature/humidity conditions without excessive moisture loss, especially when a live load generates heat, leading to limited temperature/humidity ranges and compromised utility.
Innovation Solution
A temperature control system with a heat exchanger that mixes compressed, condensed refrigerant (cold fluid) and compressed refrigerant gas (hot fluid) to control the temperature differential between the heat exchanger and the chamber air, reducing moisture loss through condensation and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling coil is used to cool the chamber air, then the temperature is reduced, but excessive moisture is removed from the air through condensation
Solution Approach 1:
The patent changes the temperature parameter of the refrigerant by mixing cold refrigerant (from the evaporator) with hot refrigerant (from the compressor discharge) to create a warm refrigerant mixture. This parameter change allows the cooling coil to cool the chamber air while maintaining its temperature above the dew point, thereby preventing condensation and moisture loss from the air.
Solution Approach 2:
The patent creates a composite refrigerant system by combining two different temperature states of the same refrigerant (cold liquid refrigerant and hot vapor refrigerant) into a single cooling coil system. This composite approach allows the coil to simultaneously provide cooling while avoiding the harmful condensation effect that would occur with a single cold coil.
2Loss of substance
If steam is added to replace condensed moisture, then humidity is maintained, but the cooling load increases due to sensible heat from the steam
Solution Approach 1:
The patent applies preliminary anti-action by preventing condensation in the first place through the use of warm refrigerant. By maintaining the cooling coil temperature above the dew point, the system avoids the need for subsequent moisture replacement and the associated cooling load increase that would result from adding steam or moisture to the chamber.
3Temperature
If the evaporating pressure is set based on the lowest temperature required, then the cooling capability is sufficient, but the cooling coil temperature is significantly below the dew point at high temperature/humidity conditions
Solution Approach 1:
The patent dynamically changes the temperature parameter of the refrigerant in the cooling coil by adjusting the mixing ratio of cold and hot refrigerant. Based on chamber conditions, the system can maintain the coil temperature above the dew point during high temperature/humidity operation while still achieving the required cooling effect, thereby eliminating condensation without sacrificing cooling capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for efficient cooling without significant moisture removal, improving system efficiency and accommodating higher heat dissipation loads while maintaining precise temperature and humidity control.
Implementation Method 1
a heat exchanger (e.g., an evaporator) positioned to communicate with the air in the work space
Implementation Method 2
The refrigerant is expanded from a liquid to a vapor at a controlled pressure
Implementation Method 3
a source of cold fluid (e.g., a compressed, condensed, and throttled refrigerant) coupled to the heat exchanger
Implementation Method 4
a source of hot fluid (e.g., compressed refrigerant gas) coupled to the heat exchanger
Data Source
AI summary
A test chamber that is capable of operating in a mode where the temperature of the chamber is efficiently cooled without removing a substantial amount of moisture from the air. In one aspect, the test chamber includes a structure defining a work space having air, and a temperature control system (e.g., a refrigeration system having a compressor, a condenser, and an evaporator valve). The temperature control system includes a heat exchanger (e.g., an evaporator) positioned to communicate with the air in the work space, a source of cold fluid (e.g., a compressed, condensed, and throttled refrigerant) coupled to the heat exchanger, a source of hot fluid (e.g., compressed refrigerant gas) coupled to the heat exchanger, and a controller for controlling a mixture of cold fluid and hot fluid entering the heat exchanger (e.g., by adjusting a cold fluid valve and/or a hot fluid valve). In order to limit the loss of humidity caused by condensation on the heat exchanger, it is preferred that the controller is programmed such that the temperature of the mixture entering the heat exchanger is controlled to limit a temperature differential between the heat exchanger and the air in the work space.